(1) Field of the Invention
The invention relates to a teaching tool for a robot arm for wafer reaction ovens, and more particularly to a block gauge which provides multiple contact points to blind calibrate a correct position of a robot arm in a sealed wafer reaction oven.
(2) Description of the Prior Art
While utilizing a sealed wafer oven or chamber in the wafer-manufacturing industry, a robot arm is usually applied to handle wafers into or out of the oven through an openable door of the oven. Referring now to FIG. 1 and FIG. 2, a transverse-sectional top view and a cross-sectional side view are shown respectively for a robot arm 2 located at a correct position, or say an anchoring position, in a wafer reaction oven 1. As shown, a wafer 3 is carried by a blade 21 of the robot arm 2 and it can be seen that the only passage for the robot arm 2 to enter or leave the oven 1 is a door 10 of the oven 1.
As illustrated in FIG. 2, it is clear that the wafer 3 is handled by the blade 21 of the robot arm 2 from a lower position (negative z axis direction). From FIG. 1, the wafer 3 in the oven 1 is rested upon an imaged surface formed by a plurality of pins 41 extruding from the tray 4 and also toward a center of the tray 4. In the operation of the oven 1, the anchoring position for the wafer 3 in the oven is essentially important. For any deviation of the wafer 3 away from the anchoring position, manufacturing defects in wafer uniformity are quite possible, and also possible collisions with the oven 1 during the wafer""s moving can be foreseen. It is obvious that both types of aforesaid situations will definitely lead to a lower yield of the wafer manufacturing process in the oven 1.
To avoid any possible deviation of the wafer 3, a calibration upon the robot arm 2 with respect to the tray 4 is required. Referring to FIG. 1 and FIG. 2, the correct relationship including the anchoring position among the robot arm 2, the wafer 3, the tray 4 and the oven 1 is shown. As shown, while the robot arm 2 holding a wafer 3 right at the anchoring position, a front edge 201 of a handle 20 of the robot arm 2 spaces a distance W to the door 10 of the oven 1, and an upper edge 211 of the blade 21 of the robot arm 2 spaces a distance h to a floor 221 inside the oven 1. Also in the correct relationship, the blade 21 of the robot arm 2 is located along a center line LL of the tray 4 and is held horizontally.
After a maintenance upon the robot arm 2 or any component of the oven 1, a calibration of the robot arm 2 with respect to the tray 4 for the wafer 3 reaching the anchoring position inside the oven 1 is required. Thereby, reference coordinate data about the anchoring position can be provided to a control system for coordinating the moving of the robot arm 2 in the following operation. In the art of the calibration upon such ovens, a calibration process or so-called a teaching process includes a step of retrieving the tray 4 from the oven 1, a step of placing a wafer 3 onto the anchoring position on the imaged surface formed by the pins 41 of the tray 4, a step of relocating the tray 4 as well as the wafer 3 into the oven 1, a step of moving the blade 21 of the robot arm 2 to the anchoring position under the wafer 3, and a step of the control system recording the coordinates of the blade 21.
However, in the calibration of the conventional robot arm 2, because the oven 1 is not disassembled at the same time, the only means that an operator can utilize to observe the position relationship inside the oven 1 is the door 10 of the oven 1. Though an electric torch can be used to help the eye-sight, yet the anchoring position of the wafer 3 is deep inside the oven 1 so that vision difficulty during the calibration can be expected. Therefore, a second calibration upon the robot arm 2 is usually needed after a short time of normal operation by investigating the wafer 3 quality produced from the oven 1.
Apparently, too many uncertainties exist in the aforesaid traditional calibration method of the robot arm 2. Definitely, if any inaccuracy occurs during the calibration, following wafer manufacturing process will be affected and thus lead to a cost hike in material preparation.
Accordingly, it is a primary object of the present invention to provide a teaching tool for a robot arm for wafer reaction ovens, by which multiple contact points can be provided to blind calibrate the correct position of the robot arm in a sealed wafer reaction oven so as to avoid possible yield reduction and cost up from an ill-calibration.
The teaching tool for a robot arm for wafer reaction ovens in accordance with the present invention is formed as a unique piece for being applied to anchor a robot arm with a blade with respect to a tray located inside a reaction oven. While in calibrating, the teaching tool is placed at an upper conjunction between a handle of the robot arm and the blade, and then the teaching tool as well as the robot arm can be fed to the reaction oven through a door of the reaction oven by allowing a portion of the teaching tool and the blade to reach an anchoring position inside the reaction oven. In the present invention, the teaching tool is to perform a stop structure for maintaining a correct position relationship among the reaction oven, the tray and the robot arm.
In accordance with the present invention, the teaching tool is characterized on that: the teaching tool provides thereof an upper flange for maintaining a spacing between the handle and the door, the teaching tool provides thereof a position width for keeping the teaching tool aligning with a center line of the tray by plugging a central passage of the tray, and the teaching tool further comprises thereof a lower tunnel aligning with the center line for allowing the blade to contact closely and horizontally therefrombelow and thus for maintaining a position height between the blade and a floor of the reaction oven.
In one embodiment of the present invention, the lower tunnel of the teaching tool can be complementary in shape to the blade at said upper conjunction.
In one embodiment of the present invention, the teaching tool can be shaped as a block gauge.
In one embodiment of the present invention, the portion of the teaching tool that enters the reaction oven while in calibrating can have a height just to plug the door of the reaction oven.
In one embodiment of the present invention, the upper flange and the handle can be surface-contacted, i.e. surface-to-surface contacted, and also the upper flange and the door can be also surface-contacted.
In one embodiment of the present invention, the teaching tool and the central passage of the tray can be surface-contacted for maintaining the position width.